Chemistry

ELECTROLYTIC CELLS AND ELECTROLYSIS OF SPECIFIED ELECTROLYTES

The passage of electricity through the electrolytes in their molten or dissolved state can cause chemical changes under suitable conditions. For example, the passage of electricity through the acidified water results in the formation of hydrogen and oxygen gases. The process of chemical decomposition of the electrolyte by he passage of electricity through its molten …

ELECTROLYTIC CELLS AND ELECTROLYSIS OF SPECIFIED ELECTROLYTES Read More »

Electrolysis

When an electric current is passed through an electrolyte solution, the ions of the electrolyte undergo chemical changes at the respective electrodes. The chemical reaction carried out by passing electricity is called electrolysis. it is important that we familiarize ourselves with different terms that we are going to use to explain different phenomena. It is …

Electrolysis Read More »

IONIC THEORY

IONIC THEORY To account for the phenomena of electrolysis the Ionic Theory was put forward by Arrhenius in 1880. The theory states that electrolytes are made up of ions, which are built up in certain patterns called crystal lattice. When these substances dissolve in water, the structure is destroyed and the ions are set free …

IONIC THEORY Read More »

BALANCING OF REDOX REACTIONS

Balancing by Ion Electron or Half Reaction Method We are familiar with the balancing of chemical equations by inspection method. However, inspection method may not be useful for balancing the redox equations because in these equations, we have to keep in mind the conservation of charge as well as conservation of mass. The redox equations, …

BALANCING OF REDOX REACTIONS Read More »

Concept of Oxidation and Reduction

Classical Concept of Oxidation and Reduction In our daily life we come across processes like rusting of iron articles, fading of the colour of the clothes, burning of the combustible substances such as cooking gas, wood, coal, etc. All these processes fall in the category of redox reactions. A large number’ of industrial processes like, …

Concept of Oxidation and Reduction Read More »

PERIODIC TRENDS IN PHYSICAL PROPERTIES

Most of the properties of the elements such as atomic volume, atomic size, ionization enthalpy, electron affinity and electronegativity are directly related to the electronic configuration of the atoms. These properties undergo periodic variation with the change in the atomic number within a period or a group. These properties indirectly control the physical properties such …

PERIODIC TRENDS IN PHYSICAL PROPERTIES Read More »

PERIODICITY

THE NEED FOR CLASSIFICATION OF ELEMENTS Before the beginning of eighteenth century, only a very few elements were known and it was quite easy to study and remember their individual properties. In 1800, only 31 elements were known. This number of elements grew to 63 by 1865. With the discovery of large number of elements …

PERIODICITY Read More »

AMINES AND AMIDES

AMINES It has a functional group of NH2. GENERAL MOLECULAR FORMULAR/STRUCTURE It has a general molecular formula of RNH2 or structure of R – N – H H PREPARATION: They are derivatives of ammonia where one or more hydrogen atoms have been replaced by alkyl or aryl groups e.g. RNHz, R2NH. CLASSIFICATION: Amines can …

AMINES AND AMIDES Read More »

CARBOHYDRATES

Carbohydrates are naturally occurring organic compounds containing carbon, hydrogen and oxygenwith oxygen in the ratio 1:2 as in water. The general molelcular formula of carbohydrates is Cx(H2O)y or CxH2yOy. Carbohydrates are generally polydroxyl aldehydes, ketones or any compound that on hydrolysis yields any of the polyhydroxides. They are synthesized in green plants by photosynthesis. …

CARBOHYDRATES Read More »

NATURAL AND SYNTHETIC POLYMERS

NATURAL AND SYNTHETIC POLYMERS Polymerisation (addition and condensation) plastics. Thermosplastic and thermosetting polymers, resins. Polymer is the final product, macromolecule of high molecular mars. It consists of a repeating units and its general molecular formula may be represented as [repeating units]n where n is a very large whole number. N.B:- All polymers are …

NATURAL AND SYNTHETIC POLYMERS Read More »

Fats and Oils As Higher Esters

Sources, properties and uses detergents and soaps Structure, their mode and action. Fats and oils belong to a general group of compounds known as lipids. SOURCES Fats are solids that usually come from animals e.g. Tallow (mutton fat). Oils are liquids that come from plants e.g. vegetable oil, coconut oil etc. Both fat and oil …

Fats and Oils As Higher Esters Read More »

ALKANOIC ACIDS

ALKANOATES General molecular formula, nomenclature, preparation, properties and uses. SOURCES The alkanoic acid or carboxylic acids are also called fatty acids because some of them are found in natural fats and oils. They contain the functional group called carboxy group. NOMENCLATURE The IUPAC name of each homologue is obtained by changing the “-e” …

ALKANOIC ACIDS Read More »

ALKANOLS

SOURCES OF ALKANOLS – From destructive distillation wood. – From starchy food and sugar General molecular formular Alkanol is a homologous series with general molecular formular of Cn H2n+1OH or ROH. Or (CnH2n+2O). Nomenclature The names of alkanols are obtained by substituting “e” in alkanes with “Ol” in alkanol e.g. methanol (CH3OH), ethanol …

ALKANOLS Read More »

AROMATIC HYDROCARBONS

Benzene: Benzene is a typical aromatic compound with molecular formula of C6H6. It has the structure of: Preparation From coal tar: The destructive distillation of coal produced coal tar which contain benzene From petreoleum; The dehydrogenated of alkane using valladim (v) oxide (v2O5) as catalyst at 500oC and 20 atmos give benzene C6H14 V2O2C6H6 + …

AROMATIC HYDROCARBONS Read More »

ALKYNES

Alkynes are the homologous series of unsaturated hydrocarbon with a general molecular formua CnH2n-2. Alkynes show a high degree of unsaturation than alkenes, hence,t hey are chemically more reactive than the corresponding alkenes or alkanes. Examples are : H H – C = C – H HC – C = C- H [ Ethyne. …

ALKYNES Read More »

Unsaturated Hydrocarbons – Alkenes

UNSATURATED HYDROCARBONS These are hydrocarbons in which carbon atoms join with each other by multiple bonds. The multiple bond can be double bonds e.g Alkene or triple bonds e.g Alkyne. Ethene2 .Ethyne H – C = C – H H – C = C – H H H. Alkenes e.gEthene Nomenclature The process of naming …

Unsaturated Hydrocarbons – Alkenes Read More »

Saturated Hydrocarbons

Saturated Hydrocarbons Saturated hydrocarbons are hydrocarbons consisting of carbon chains with single bond between them in which carbon joins with another carbon by single covalent bond e.g Alkanes ( like ethane C2H6, propane C3H8 ) H H HHH H – C C – H H – C – C – C – H …

Saturated Hydrocarbons Read More »

SIMPLE MACHINE

Definition of Simple Machine A machine is a tool or device that makes work easier. It is defined as a tool which uses force applied (effort) at one point to overcome another resisting force (effort) at another point. Examples of machine include: a plier, the human arm, a gear, a pulley etc. Types of …

SIMPLE MACHINE Read More »

AIR AND COMBUSTION

Percentage of Oxygen in Air We have read that Air consists mainly of molecules of oxygen and nitrogen with important yet trace amounts of other gases. We know that the combustion of organic material requires oxygen. The idea here is to capture a quantity of air in a measured and isolated volume and then use …

AIR AND COMBUSTION Read More »

AN ALKALI

Alkali is pronounced like alcohol, with ‘lie’ at the end instead of ‘hol’. An alkali is any substance which produces OH– ions in water. OH– ions are called hydroxide ions. If there are excess of (OH)– ions when a compound is dissolved in water, the solution is called a base or an alkaline solution. A base …

AN ALKALI Read More »